A light guide is disclosed. The light guide may comprise a wedge shape. The light guide includes a light receiving surface, a light transmission region, a transition region, and a light emission region. Light emission region includes a first major surface and an opposing second major surface. The light emission region may include a plurality of steps disposed along a length of one or both of the major surfaces. The light emission region may also include a plurality of vertically-extending flutes along one or both of the major surfaces. A luminaire assembly incorporating the light guide is also disclosed.

An optical device has a light path for guiding a light beam along a circular arc. The light path has at least one light path segment having a number of light path elements arranged tangentially along the light path. Each of the light path elements is at least partially limited in a radial direction by a first interface. The first interfaces of a respective light path segment are each configured to reflect at least light incident from the light path at an angle of incidence greater than a predetermined angle onto the respective first interface to keep a light beam propagating along the light path in a direction of travel predetermined for the respective light path segment on the light path. A first tangential end of the first interfaces is spaced radially further apart from the center of the circular arc than a second tangential end.

An imaging directional backlight apparatus including a waveguide, a light source array, for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, in which the steps may further include extraction features optically hidden to guided light, propagating in a first forward direction. Returning light propagating in a second backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. The directional backlight may be arranged to switch between at least a first wide angular luminance profile mode and a second narrow angular luminance profile mode. The directional backlight is arranged to illuminate an LCD with a bias electrode arranged to switch liquid crystal directors in black state pixels between a first wide angular contrast profile mode and a second narrow angular contrast profile mode. Performance of privacy operation for off-axis snoopers is enhanced in comparison to displays with only directional backlights or switchable contrast properties.

A directional privacy display may include a waveguide; and an array of light sources and spatial light modulator that operate in a time sequential manner. The waveguide may include light extraction features arranged to direct light from an array of light sources by total internal reflection to an array of viewing windows and a reflector arranged to direct light from the waveguide by transmission through extraction features of the waveguide to the same array of viewing windows. First and second phases may be temporally multiplexed with respective primary and secondary images and primary and secondary angular illumination distributions. An efficient and bright privacy display may be provided with obscured primary image visibility for off-axis observers.

An imaging directional backlight apparatus includes a waveguide and light source array for providing large area directed illumination from localized light sources. The waveguide may include a stepped structure in which steps may include extraction features optically hidden to guided light, propagating in a forward direction. Returning light propagating in a backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources and defines the relative positions of system elements and ray paths. Alignment of the waveguide to mechanical and optical components may be provided by surface relief features of the waveguide arranged in regions adjacent the input surface and intermediate the light emitting regions of the light sources. Efficient, uniform operation may be achieved with low cross talk for application to autostereoscopic and privacy modes of operation.

An imaging directional backlight apparatus includes a waveguide and a light source array, providing large area directed illumination from localized light sources. The waveguide may include a stepped structure, and the steps may further include extraction features optically hidden to guided light, propagating in a forward direction. Returning light propagating in a backward direction may be refracted, diffracted, or reflected by the features to provide discrete illumination beams exiting from the top surface of the waveguide. Viewing windows are formed through imaging individual light sources and define the relative positions of system elements and ray paths. The imaging directional backlight apparatus further includes a control system for controlling the light output directional distribution in an automotive or vehicle environment in dependence on the output from sensors mounted on the vehicle. The control system is arranged to control the light output direction distribution of portable directional displays co-located with the vehicle.

An illumination module comprises a semiconductor light source and a light guide, which comprises a solid body with essentially parallel entry and exit faces and side faces extending between the entry and exit faces; and wherein the entry face receives light emitted by the semiconductor light source; the exit face is offset from the entry face and the area of the exit face exceeds the area of the entry face; a first side face comprises a uniform plane subtending an angle of inclination to the entry face; a second side face, opposite to the first side face, comprises a plurality of offset sub-faces, each sub-face subtends an angle of inclination relative to the entry face; and the inclined faces are formed so that the direction of light leaving the exit face is essentially the same as the direction of light entering the entry face.

A light guide is disclosed. The light guide may comprise a wedge shape. The light guide includes a light receiving surface, a light transmission region, a transition region, and a light emission region. Light emission region includes a first major surface and an opposing second major surface. The light emission region may include a plurality of steps disposed along a length of one or both of the major surfaces. The light emission region may also include a plurality of vertically-extending flutes along one or both of the major surfaces. A luminaire assembly incorporating the light guide is also disclosed.

A privacy display comprises a luminance-privacy arrangement and a contrast-privacy arrangement. In a privacy mode of operation, ambient light levels are detected and a visual security level is calculated. At and above a visual security level threshold the luminance-privacy arrangement is operable and below the threshold both the luminance-privacy and contrast-privacy arrangements are operable. Image quality for on-axis users is optimised and high levels of visual security are achieved for off-axis snoopers over a wide range of display illuminance conditions.

A virtual image display device includes a video image element that displays an image, and a light-guiding member that guides video image light from the video image element by reflection and transmission at a plurality of light-guiding surfaces. Among the plurality of light-guiding surfaces, with respect to an incident-side light-guiding surface and an emission-side light-guiding surface that are adjacent to each other, and an opposing light-guiding surface that faces the incident-side light-guiding surface and the emission-side light-guiding surface, a thickness from the incident-side light-guiding surface to the opposing light-guiding surface is caused to be smaller than a thickness from the emission-side light-guiding surface to the opposing light-guiding surface.